Sunquist and Sunquist (2009) recognized 37 species in the cat family (Felidae), but noted that this number would likely grow somewhat as further taxonomic studies confirm that some currently recognized species actually are composed of distinct populations that warrant recognition as species. Although the number of recognized species has been relatively stable for a century or two, the recognition of genera has been far more dynamic, with the number generally accepted ranging from just two or three to more than a dozen.
There are native felids across all major regions of the Earth except for Australasia and the polar regions (domestic cats have been introduced to many remote oceanic islands and Australia). They may be found from sea level to 6000 meters and in habitats ranging from deserts to savannahs to tropical rainforests, temperate forests, and boreal forests, but around 90% of felid species are associated with forests and woodlands. Some species have relatively narrow geographic and ecological ranges, but a few are extreme generalists. The Puma (Puma concolor) has a range spanning more than 100 degrees of latitude from the Canadian Yukon to the Straits of Magellan and is found from the moist coniferous forests of British Columbia in Canada to the deserts of the southwestern United States, the tropical forests of Central and South America, and south to the cold, dry grasslands of Patagonia. Leopards (Panthera pardus) have a similarly broad distribution in the Old World, ranging from South Africa to the Russian Far East and occurring in habitats from desert to tropical forest. The Colocolo (Leopardus colocolo) and Leopard Cat (Prionailurus bengalensis) (of South America and Asia, respectively) are also notable habitat generalists, although in the case of the Colocolo what is currently treated as a single species may in fact be several cryptic species.The Leopard Cat has the broadest distribution of all small Asian felids, occurring from southern India to the islands of the Sunda Shelf and north to the Russian Far East and ranging across diverse habitats from sea level to 3000 meters in the Himalayas.
The extant felids are relatively homogeneous in their morphology, so much so that the skeletons of two species as different as a Lion (Panthera leo) and a Tiger (Panthera tigris) would be difficult for a non-specialist to distinguish. A typical felid has a rounded head, a relatively flat face, facial whiskers, large eyes and ears, and a sleek and streamlined body with muscular legs. That said, the felids as a group are remarkably variable in size, probably more so than any other mammal family, ranging acoss two orders of magnitude in mass from the 2 to 3 kilogram Black-footed Cats (Felis nigripes), Kodkods (Leopardus guigna), and Rusty-spotted Cats (Prionailurus rubiginosus) to 300 kilogram Tigers. In most species, males tend to be around 5 to 10% larger than females. Many felid species with large geographic ranges exhibit size variation consistent with Bergman's Rule. For example, Pumas from low latitudes (i.e., closer to the equator) have skulls that average as much as 25% shorter than higher latitude Pumas and an even greater effect of latitude is seen in body weight.
Most felids are nocturnal and nearly all felids are solitary as adults (with only Lions being truly social, although Cheetahs [Acinonyx jubatus] are also somewhat social). Both vocalizations and visual signals are used extensively in communication. Felids are believed to have a relatively poor sense of smell relative to other carnivores, but use scent-marking extensively to communicate with conspecifics.
Felids are sometimes referred to as hypercarnivores because they require a much higher proportion of protein in their diet than do most other mammals. The largest felids are predators of very large mammals. The dominant large cats are the Lion in Africa, the Tiger in Asia, and the Jaguar (Panthera onca) in South America. The medium-sized cats such as the Puma, Snow Leopard (Panthera uncia), and Leopard are able to kill prey their own size, but much of their diet consists of smaller prey between 2 and 40 kilograms and their diets tend to include a much larger range of species than do the diets of the big cats, which tend to feed on just a few species in any particular ecosystem. Small felids, such as Ocelots (Leopardus pardalis), Bobcats (Lynx rufus), Black-footed Cats, and Jungle Cats (Felis chaus), also feed on mammals, but their diets frequently include birds, reptiles, amphibians, and insects as well, with most prey items less than one kilogram. A few small cats are relatively specialized predators, e.g., the Fishing Cat (Prionailurus viverrinus), which captures fishes and frogs by wading in shallow water or waiting on the bank, often plunging its head completely underwater to seize a fish. Fishing Cats have reportedly been seen swimming underwater to catch coots or ducks. Servals (Leptailurus serval) are specialized on small mammals and Canadian Lynx (Lynx canadensis) feed heavily on Snowshoe Hares (Lepus americanus).
Coat pattern is highly variable both among and within felid species. Especially striking intraspecific variation is the melanism that has been recorded for a number of felid species living in tropical humid and densely vegetated habitats. Best known are the "black panthers", which are melanistic Leopards (in the Old World) or Jaguars (in the New World).
Many species of felids have declined dramatically over the past century or two due to human impacts, with declining ranges and shrinking populations resulting from habitat loss, declining prey populations, and direct persecution for trade, predator control, and sport. Some felid species are believed to be naturally rare (e.g., the extremely poorly known Bay Cat (Catopuma badia) of Borneo and the three smallest felids, the Kodkod of Chile and Argentina, the Rusty-spotted Cat of India and Sri Lanka, and the Black-footed Cat of South Africa), making them more vulnerable to new threats. Sunquist and Sunquist (2009) provided an overview of the conservation threats facing many of the world's felids.
(Sunquist and Sunquist 2009 and references therein)